feat: add experimental support for generics directive (#477)

.changeset/twelve-bulldogs-peel.md

@@ -0,0 +1,5 @@
+---
+"svelte-eslint-parser": minor
+---
+
+feat: add experimental support for generics directive

README.md

@@ -169,6 +169,24 @@ module.exports = {
 }
 ```
 
+### parserOptions.svelteFeatures
+
+You can use `parserOptions.svelteFeatures` property to specify how to parse related to Svelte features. For example:
+
+```json
+{
+    "parser": "svelte-eslint-parser",
+    "parserOptions": {
+        "svelteFeatures": {
+            /* -- Experimental Svelte Features -- */
+            // Whether to parse the `generics` attribute.
+            // See https://github.com/sveltejs/rfcs/pull/38
+            "experimentalGenerics": false
+        }
+    }
+}
+```
+
 ### Runes support
 
 ***This is an experimental feature. It may be changed or removed in minor versions without notice.***

docs/AST.md

@@ -172,6 +172,7 @@ interface SvelteStartTag extends Node {
     | SvelteDirective
     | SvelteStyleDirective
     | SvelteSpecialDirective
+    | SvelteGenericsDirective
   )[];
   selfClosing: boolean;
 }
@@ -362,6 +363,19 @@ interface SvelteSpecialDirectiveKey extends Node {
 }
 ```
 
+### SvelteGenericsDirective
+
+This is the generics directive node.
+
+```ts
+interface SvelteGenericsDirective extends BaseNode {
+  type: "SvelteGenericsDirective";
+  key: SvelteName & { name: "generics" };
+  params: TSESTree.TSTypeParameter[];
+  parent: SvelteStartTag & { parent: SvelteScriptElement };
+}
+```
+
 ## Texts and Literals
 
 ### SvelteText

src/ast/html.ts

@@ -1,4 +1,5 @@
 import type ESTree from "estree";
+import type { TSESTree } from "@typescript-eslint/types";
 import type { BaseNode } from "./base";
 import type { Token, Comment } from "./common";
 
@@ -32,6 +33,7 @@ export type SvelteHTMLNode =
   | SvelteDirective
   | SvelteStyleDirective
   | SvelteSpecialDirective
+  | SvelteGenericsDirective
   | SvelteDirectiveKey
   | SvelteSpecialDirectiveKey
   | SvelteHTMLComment;
@@ -142,6 +144,7 @@ export interface SvelteStartTag extends BaseNode {
     | SvelteDirective
     | SvelteStyleDirective
     | SvelteSpecialDirective
+    | SvelteGenericsDirective
   )[];
   selfClosing: boolean;
   parent: SvelteElement | SvelteScriptElement | SvelteStyleElement;
@@ -651,3 +654,9 @@ export interface SvelteSpecialDirective extends BaseNode {
   expression: ESTree.Expression;
   parent: SvelteStartTag /* & { parent: SvelteSpecialElement } */;
 }
+export interface SvelteGenericsDirective extends BaseNode {
+  type: "SvelteGenericsDirective";
+  key: SvelteName & { name: "generics" };
+  params: TSESTree.TSTypeParameterDeclaration["params"];
+  parent: SvelteStartTag /* & { parent: SvelteScriptElement } */;
+}

src/context/fix-locations.ts

@@ -0,0 +1,73 @@
+import type * as ESTree from "estree";
+import type { Comment, Locations, Token } from "../ast";
+import type { Context } from ".";
+import { traverseNodes } from "../traverse";
+
+/** Fix locations */
+export function fixLocations(
+  node: ESTree.Node,
+  tokens: Token[],
+  comments: Comment[],
+  offset: number,
+  visitorKeys: { [type: string]: string[] } | undefined,
+  ctx: Context,
+): void {
+  if (offset === 0) {
+    return;
+  }
+  const traversed = new Set<any>();
+  traverseNodes(node, {
+    visitorKeys,
+    enterNode: (n) => {
+      if (traversed.has(n)) {
+        return;
+      }
+      traversed.add(n);
+      if (traversed.has(n.range)) {
+        if (!traversed.has(n.loc)) {
+          // However, `Node#loc` may not be shared.
+          const locs = ctx.getConvertLocation({
+            start: n.range![0],
+            end: n.range![1],
+          });
+          applyLocs(n, locs);
+          traversed.add(n.loc);
+        }
+      } else {
+        const start = n.range![0] + offset;
+        const end = n.range![1] + offset;
+        const locs = ctx.getConvertLocation({ start, end });
+        applyLocs(n, locs);
+        traversed.add(n.range);
+        traversed.add(n.loc);
+      }
+    },
+    leaveNode: Function.prototype as any,
+  });
+  for (const t of tokens) {
+    const start = t.range[0] + offset;
+    const end = t.range[1] + offset;
+    const locs = ctx.getConvertLocation({ start, end });
+    applyLocs(t, locs);
+  }
+  for (const t of comments) {
+    const start = t.range[0] + offset;
+    const end = t.range[1] + offset;
+    const locs = ctx.getConvertLocation({ start, end });
+    applyLocs(t, locs);
+  }
+}
+
+/**
+ * applyLocs
+ */
+function applyLocs(target: Locations | ESTree.Node, locs: Locations) {
+  target.loc = locs.loc;
+  target.range = locs.range;
+  if (typeof (target as any).start === "number") {
+    delete (target as any).start;
+  }
+  if (typeof (target as any).end === "number") {
+    delete (target as any).end;
+  }
+}

src/context/index.ts

@@ -29,9 +29,12 @@ export class ScriptsSourceCode {
 
   public readonly attrs: Record<string, string | undefined>;
 
-  private _separate = "";
-
-  private _appendScriptLets: string | null = null;
+  private _appendScriptLets: {
+    separate: string;
+    beforeSpaces: string;
+    render: string;
+    generics: string;
+  } | null = null;
 
   public separateIndexes: number[] = [];
 
@@ -49,16 +52,28 @@ export class ScriptsSourceCode {
     if (this._appendScriptLets == null) {
       return this.raw;
     }
-    return this.trimmedRaw + this._separate + this._appendScriptLets;
+    return (
+      this.trimmedRaw +
+      this._appendScriptLets.separate +
+      this._appendScriptLets.beforeSpaces +
+      this._appendScriptLets.render +
+      this._appendScriptLets.generics
+    );
   }
 
-  public getCurrentVirtualCodeInfo(): { script: string; render: string } {
+  public getCurrentVirtualCodeInfo(): {
+    script: string;
+    render: string;
+    generics: string;
+  } {
     if (this._appendScriptLets == null) {
-      return { script: this.raw, render: "" };
+      return { script: this.raw, render: "", generics: "" };
     }
     return {
-      script: this.trimmedRaw + this._separate,
-      render: this._appendScriptLets,
+      script: this.trimmedRaw + this._appendScriptLets.separate,
+      render:
+        this._appendScriptLets.beforeSpaces + this._appendScriptLets.render,
+      generics: this._appendScriptLets.generics,
     };
   }
 
@@ -68,22 +83,30 @@ export class ScriptsSourceCode {
     }
     return (
       this.trimmedRaw.length +
-      this._separate.length +
-      this._appendScriptLets.length
+      this._appendScriptLets.separate.length +
+      this._appendScriptLets.beforeSpaces.length +
+      this._appendScriptLets.render.length +
+      this._appendScriptLets.generics.length
     );
   }
 
-  public addLet(letCode: string): { start: number; end: number } {
+  public addLet(
+    letCode: string,
+    kind: "generics" | "render",
+  ): { start: number; end: number } {
     if (this._appendScriptLets == null) {
-      this._appendScriptLets = "";
-      const currentLength = this.getCurrentVirtualCodeLength();
+      const currentLength = this.trimmedRaw.length;
       this.separateIndexes = [currentLength, currentLength + 1];
-      this._separate += "\n;";
-      const after = this.raw.slice(this.getCurrentVirtualCodeLength());
-      this._appendScriptLets += after;
+      const after = this.raw.slice(currentLength + 2);
+      this._appendScriptLets = {
+        separate: "\n;",
+        beforeSpaces: after,
+        render: "",
+        generics: "",
+      };
     }
     const start = this.getCurrentVirtualCodeLength();
-    this._appendScriptLets += letCode;
+    this._appendScriptLets[kind] += letCode;
     return {
       start,
       end: this.getCurrentVirtualCodeLength(),